This invention relates to suspension and shock absorber systems for vehicles, and more particularly to such systems for motor homes, recreational vehicles, trailers, and trucks.
Suspension and shock absorber systems are known which provide a controlled and smooth ride for automobiles. Many of these systems are not readily adaptable to larger motor vehicles, however, since they cannot handle the greater loads of larger vehicles and still provide a controlled and smooth ride. Prior art air suspension systems may be capable of handling large loads while providing a smooth ride, but they are complicated and expensive.
The suspension and shock absorber systems of large motor vehicles such as mobile homes and recreational vehicles must be capable of handling the heavy loads due to the weight of the vehicles while still providing a controlled ride. The prior art all metal suspension systems are incapable of handling both the heavy loads and shock forces while at the same time providing a smooth and stable ride to the occupants traveling in the vehicle. Since such prior art systems are incapable of both handling the heavy loads while at the same time providing a smooth and stable ride, the systems are generally designed to only handle the heavy loads. Thus, the ride for occupants in such vehicles is very rough when smaller roadway discontinuities are encountered by the wheels, such as tar strips and small potholes. Shocks resulting from these relatively small discontinuities are not capable of being absorbed by an all metal prior art system designed to handle the larger shock forces. The ride is thus uncomfortable for the occupants, particularly on long trips which are commonly taken with recreational vehicles.
The rough ride of a recreational vehicle poses additional problems. Since many recreational vehicles also serve as temporary living quarters for the occupants, these vehicles often have fragile items such as dishes and other glassware on counters and in cabinets. The relatively large jolts experienced by these vehicles due to the poor prior art suspension systems may damage or break fragile items.
In the past, most recreational vehicles had rear-wheel drive. Since the space within the rear axle included a differential and other heavy drive components, it was difficult to incorporate a sophisticated suspension and shock absorber system on such vehicles. More recently, front-wheel drive is being increasingly used on large motor vehicles, including mobile homes. Without the drive components in the rear axle, a compact, light weight rear axle utilizing a sophisticated suspension system can provide stable handling combined with a controlled ride.
Prior art suspension systems typically had to be sized for a particular application due to the vast differences in loads which must be carried by different types of vehicles. For example, a cargo-carrying truck would have a different suspension system than a small recreational vehicle. A large recreational vehicle such as a motor home would have a different suspension system than smaller recreational vehicles and trucks. The need to specifically size a suspension system for a particular application increases the cost of the suspension system as well as that of the vehicle itself.
One reason that specially sized suspension systems were needed for each application was the road height of the vehicle changes as the load imposed on the suspension system increases. Since a large truck may carry a larger load than a small truck, a relatively large truck may have an insufficient road height if it is fully loaded. However, the same suspension system on a smaller truck may have an acceptable road height even if it fully loaded. Therefore, it is desirable to provide a suspension system in which the road height may be readily changed to accommodate varying loads so that the suspension system may be used on a wide variety of vehicles.
Another shortcoming of prior art systems is that shock forces imposed on the wheels are readily transmitted to the vehicle's frame and thus to the occupants despite the use of a suspension and shock absorber system. Therefore, it is desirable to minimize the transmission of high impact shock forces from the suspension and shock absorber system to the vehicular frame and body.